A hearing aid is designed to amplify sound for a user, make speech more intelligible, and/or correct hearing impairments. Feedback, a howling caused by sound (particularly high frequency sound) leaking and being amplified again, may be a problem for severe hearing losses. In hearing aids, feedback arises when a part of the receiver signal captured by the hearing aid's microphone, gets amplified in the hearing aid and starts to loop through the system. When feedback occurs, it results in a disturbingly loud tonal signal. Feedback is more likely to occur when the hearing aid volume is increased, when the hearing aid fitting is not in its proper position or when the hearing aid is brought close to a reflecting surface (e.g., when using a mobile phone). Adaptive feedback cancellation algorithms are techniques that estimate the transmission path between loudspeaker and microphone(s). This estimate is then used to implement a neutralizing electronic feedback path that suppresses the tonal feedback signal.
A primary issue that can minimize the effectiveness of hearing aids is called the compression effect. The compression effect takes place when the amplification needed to make quiet sounds audible, if applied to loud sounds, damages the inner ear (cochlea). Louder sounds are therefore reduced giving a smaller audible volume range and hence inherent distortion. However, hearing protection can also be provided by an overall cap to the sound pressure and impulse noise suppression, which is available in some high-end hearing aids.
The above-described background relating to hearing aids is merely intended to provide a contextual overview of hearing aid technology, and is not intended to be exhaustive. Other context regarding hearing aids may become further apparent upon review of the following detailed description.